Pressure gauge



Nov. 14, 1950 D. 0. DRUGE 5 QQ PRESSURE GAUGE Filed March 29, 1946 IN V EN TOR.

DANIEL o. DRUGE BY ATTQRMEYS Patented Nov. 14, 1950 UNITED STATES PATENT OFFICE 2,530,005 PRESSURE GAUGE Daniel 0. Druge, Oakland, Calif.

Application March 29, 1946, Serial No. 658,114

This invention relates to a pressure gauge, such as is used for testing of the air pressure in pneumatic tires.

The principal object of the invention is the provision of a pressure gauge so constructed as to enable the user to readily adjust the same to provide an accurate reading of the pressure.

Another. object of the invention is the provision of a tire pressure gauge so constructed that the user may quickly adjust the same without the necessity for disassembling it or using tools, so as to provide accurately setting the gauge for providing accurate readings.

A still further object of the invention is the provision of a tire pressure gauge so constructed as to facilitate its assembly, testing, and adjustment.

It is a well known fact that tire pressure gauges become inaccurate after a certain time, and many times they are incorrectly set at the start, or they may accidentally be misadjusted. Heretofore, attempts have been made to provide for adjusting tire pressure gauges, but these attempts have generally been along lines that require the disassembly of the gauge for making the adjustment or the use of a special tool or both. In most instances the procedure is so tedious, requiring repeated disassembling Y and assembling of the gauge until the desired adjustment is made, that the user abandons the job or else attempts to reconcile himself to a mediocre adjustment.

By the "present invention, the operator can make the desired adjustment within a few secends, and at the time the gauge is assembled the adjustment can be made during the time they actual air pressure is applied for testing the gauge. .In factthe .user himself may, if desired, make the adjustment while the air pressure is applied if he desires.

Other objects and advantages will appear in the description and in the drawings, such as the provision of structure facilitating the collapse of the-gauge after a reading, and the provision fora clear exposure of the pressure indicating figures and marks during a reading.

In the drawings,

Fig. 1 is a sectional view taken longitudinally through a pressure gauge with certain parts indicated in elevation.

Fig. 2 is an enlarged end elevational view of the gauge of Fig. 1 as seen from the outer, upper end thereof.

Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 1.

Fig. 4 is an enlarged sectional View taken along line 4-4 of Fig. 1.

In detail, the gauge illustrated comprises a cylinder I provided with a fitting 2 at one end thereof having a chuck 3 adapted to receive a conventional valve stem, and which fitting has an inlet 1 Claim. (Cl. 73-419) .4 extending between said chuck and the interior of the cylinder at the end of the latter carrying said fitting for admission of air under pressure into said cylinder. The said fitting 2 may be formed with an exterior annular groove into which the end 5 of the cylinder l is turned or crimped for securing said fitting to said cylinder. Also a cylindrical portion 6 of said fitting projects into said cylinder and is formed with a tapered end for providing an annular recess between the tapered sides of said end and said cylinder for receiving the cup washer 8 of a piston 9 that is reciprocable in said cylinder when said piston is at one end of its stroke and no air pressure is admitted through inlet 4.

The piston 9 is formed with a slight, radially outwardly projecting flange [9 adjacent said cup washer, and a coil spring 12 reacts between said flange and a washer IS in the end of the cylinder that is opposite said fitting 2 for yieldably urging said piston to the one end of its stroke adjacent said fitting.

The end of said cylinder l opposite fitting 2 is formed with a radially inwardly projecting flange M for holding said washer 13 in said cylinder, and between washer I3 and flange I4 is a second washer [6, while a spring friction member I! is between washers I3, l6 for a purpose to be later described more in detail.

An elongated pressure indicating element I8 is Within said cylinder l and extends longitudinally and coaxially thereof. The said element I8 is preferably flattened (Figs. 2 to 4') for the major portion of its length, and carries pressure indicating numbers and marks [9' on its flat sides. Said element extends through the washers l3, l6 and friction member I! and projects outwardly of the end of the cylinder l beyond flange M.

The end portion 20 of element l8 that is adjacent piston 9 is preferably cylindrical and is secured to the flat major portion of said element by a pin 2i. The said portion 20 terminates in a tapered end 22 that engages the piston 9. As the portion 20is preferably only slightly smaller in diameter than the inside diameter of the coil spring l2, the tapered end 22 prevents the end of said portion 28 from bumping or engaging the coils of the spring when the element I8 is pushed toward piston 9 and into engagement with the latter after the said element has been moved by the piston to an extended position for taking a reading of the pressure.

The coil spring I2 is preferably more tightly coiled at its end that is adjacent the piston 9 than the remainder of said coil. This multiple pitch in spring 12 permits a wide graduation at low pressures and a relatively wide graduation in the higher pressures without making separate springs.

The exterior of the cylinder l at the end thereof 30 lbs., thus correcting the error.

ment of the-cap at the time of the initial testing through which the pressure indicating element 1 8 extends, is threaded for threaded engagement with the interior threads on the annular flange 25 of a cap having a head 26 that is formed with a slot 2! (Fig. 2) through which the element [8 freely extends. The outline of slot 2'! substantially corresponds to the cross-sectional outline of the element I8. Thus element l8 Will not turn or rotate in the slot.

Projecting from the head 26 alongside the graduations I9 at each side of element' i8 is an indication or pointer 28. The point of this'indicationdefines the reading point on the pressure indicating element [8. By this arrangement substantially the major part of each numeral is exposed forreading, and the graduation identified by said pointeris entirely exposed. V This indicator device is movable longitudinally of the cylinder I upon rotation thereof, thus the pointers 28 thereon will change their positions relative to the graduations I9 on element l upon said movement.

-A pen or pencil clip 30 may embrace the cylinder I between the flange or sleeve 25 and a lock nutror ring 3! that is also threaded onto the cylinder l.

The spring member I! that surrounds the ele- -ment I8 is in frictional engagement with said from the valve stem, the element I8 will nevertheless stay in extended position, even though the piston 9 returns to the end of the cylinder adjacent fitting 2. After reading the graduation, or'pressure, the element I 8 is pushed back to collapsed position ready for another reading.

Assuming that the recorded or indicated pressure one particular reading is 25 lbs. but the actual-pressure is known to be 30 lbs. the operator may quickly loosen the lock nut and move the cap;to :thepoint where the indicator will read This adjustof the gauge at the factory also facilitates the workof setting the gauge. No special equipment 4 is necessary nor is it necessary to disassemble the gauge. The adjustment can be made when the pressure is against piston 9 or when the gauge is disconnected from air pressure, as desired.

It is also pertinent to'note that the cap 26 is outwardly of the end of the cylinden'l and is independent of the spring 12, which is essential to accuracy.

It is to be understood that the detailed description and drawings are not to be considered restrictive of the invention, but are merely illustrative thereof.

- a'c'oil spring extending between the OppOsite 'end of saidcylinder and'f'said' piston tending to move said piston toward said inlet, an elongated pres sure indicating element extending-throughsaid spring coaxial therewith and through thesaid oppositeend of said cylinder and pro'v'ided "wi th spaced pressure indicating marks on aside-there'- of, aninclicatorcarried on said opposite end of said cylinder and projecting outwardly of said opposite end cooperating with said element a'nd marks for indicating the mark onsaid element to be re'ad,:said indicator being movable longitudinally of said element 'independently ofsaid spring and piston for varying its position relative to said marks and locking meansfor releasabl'y securing said indicator in adjusted position-"said element including a cylindrical end portion-adjacent said piston formed with a tapered 'en'd engageable with said piston,sa'id' element including said end portion being separable from saidpiston, and friction means in said cylinder for frictionally holding said element in extended position upon movement of said piston toward said inlet, said cylindrical end portion being only'slightly less' in diameter than the diameter of said spring.

"REFER NCES CITED 5 The following re-ferences are o'f -re cord in' th'e file of this patent; UNITEDSTATES PATENTS Number Name *Date 1,438,798 Walker s Dec: l2,rli922 1,602,822 1 Kraft -Oct.:'1'2,-'1926 1,774,153 Pfeiffer 'Aug'; 26,:- 1930 2,050,084

Carliss Aug. 4,1936 

